This invention relates to a mechanical disc brake for use in a vehicle, and, particularly to a mechanical disc brake of the kind including a stationary member provided on one side of a rotatable disc, a caliper having a main body portion slidably mounted on the stationary member and an arm portion straddling the circumferential edge of the disc, a first friction pad provided on the one side of the disc and a second friction pad provided on the other side of the disc, at least one pin secured to the stationary member and extending to the other side of the disc for slidably supporting thereon the second friction pad, and an actuating lever rotatably mounted on the main body portion of the caliper.
The actuating lever is connected to a brake pedal or a brake lever through a cable, and an input force applied to the actuating lever to rotate it is converted to a linear output force which is applied to the friction pads, thereby effecting the braking action. The linear output force acts directly on the first friction pad to press the friction pad against the one side of the disc, and the reaction force generated thereby displaces the caliper so that the arm portion thereof presses the second friction pad against the disc.
In exchanging the second or the outer friction pad the caliper is displaced relative to the stationary member in the direction such that the arm portion of the caliper separates from the second friction pad to form a space therebetween, and the second friction pad is dismounted from or mounted on the pin by utilizing the space. Usually there are two circumferentially spaced parallel pins.
The construction is advantageous since the second friction pad can be exchanged very easily. However there is a problem that the caliper may be displaced due to such conditions as vibrations when operating the vehicle while the brake is in the non-actuated condition thereby forming the space between the caliper and the friction pad such that the friction pad will escape from the pin.